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Back2Basics: Understanding Closure data etc.

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(@yswami)
Posts: 948
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Aloha,
I recently purchased TraversePC survey software--they gave an excellent discount for us as a non profit organization. Very helpful folks. Just began to use it. I enter one of simplest lot of the seven lots we have. Entered the Az. and HD per the deed, the program created pretty cool drawing. The software give a summary of closure data--see screenshots. It shows error summary and there are few things that I don't understand.
1. What is "relative error?" How was this value obtained?
2. Linear error of 0.01 and how this value was obtained?
3. Closing point, why the program list point #1 as correct? Is this because that is where the last point should be for a perfect closure?
4. On the drawing…the label for the curve, T= 95.46' What does "T" stands for? What portion of the drawing does this distant represent?

Thank you as always for the guidance!

 
Posted : November 6, 2013 7:16 pm
 jaro
(@jaro)
Posts: 1721
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Relative error is the ratio of error, 588.39/0.011 although the .011 is not carried out to enough digits to get the same result the software posted.

Linear error is the calculated difference between the coordinates of point 1 and point 5
0.0066 north and 0.0088 east, the vector between them being .011 feet.

3 - yes

T= tangent, the distance between the PC and the PI
http://www.engineeringcivil.com/circular-curves.html

James

 
Posted : November 6, 2013 7:44 pm
(@beer-legs)
Posts: 1155
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Posted : November 6, 2013 7:48 pm
(@yswami)
Posts: 948
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Topic starter
 

> Relative error is the ratio of error, 588.39/0.011 although the .011 is not carried out to enough digits to get the same result the software posted.
>
> Linear error is the calculated difference between the coordinates of point 1 and point 5
> 0.0066 north and 0.0088 east, the vector between them being .011 feet.
>
> 3 - yes
>
> T= tangent, the distance between the PC and the PI
>> http://www.engineeringcivil.com/circular-curves.html
>
> James

Aloha, James & Beer Legs:

Thank you for the replies!

I was dividing 588.39/0.011 but didn't get the same result…with your confirmation I am relieved now. Engineering site url has a lot of educational information.

 
Posted : November 6, 2013 7:56 pm
 jaro
(@jaro)
Posts: 1721
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By reversing the equation -
588.39/53545 = 0.010988701

.011 by the coordinates or .01 as shown on the printout is close enough.

James

 
Posted : November 6, 2013 8:27 pm
(@yswami)
Posts: 948
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Topic starter
 

> By reversing the equation -
> 588.39/53545 = 0.010988701
>
> .011 by the coordinates or .01 as shown on the printout is close enough.
>
> James

Aloha, James: Thanks!:good:

 
Posted : November 6, 2013 8:35 pm
(@rj-schneider)
Posts: 2784
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:good: I had always thought TPC was the hands down coolest survey software that i'd seen. This is from using a VERY EARLY version of that software.

I was wondering how it was that you ran your description in one direction - gauging from the point number increment - but the azimuths run the other direction?

 
Posted : November 9, 2013 6:09 am
(@yswami)
Posts: 948
Member
Topic starter
 

> :good: I had always thought TPC was the hands down coolest survey software that i'd seen. This is from using a VERY EARLY version of that software.
>
> I was wondering how it was that you ran your description in one direction - gauging from the point number increment - but the azimuths run the other direction?

Aloha, RJS:
I am very new at this…could it be because I am using South Azimuth? In Hawaii all surveys are done clockwise from true South.

Do you still us TPC? I wonder how many surveyors here us TPC?

 
Posted : November 9, 2013 9:24 am
(@rj-schneider)
Posts: 2784
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Aloha, RJS:
I am very new at this…could it be because I am using South Azimuth? In Hawaii all surveys are done clockwise from true South.

Ahhh..I see, the old South Azimuth would answer the question.

Do you still us TPC? I wonder how many surveyors here us TPC?

No, I don't currently use TPC, and haven't for many years. Cool choice for software.

 
Posted : November 9, 2013 4:59 pm